1. Field of the Invention
This invention relates generally to a method and apparatus for making fiber optic couplers, and tapered ends to optical fibers and more particularly to a method apparatus for making fiber optic couplers having a cylindrical constant diameter midsection.
2. Brief Description of the Prior Art
The need for fiber optic devices such as couplers, tapered polarizers, and others that require the fusing or stretching of optical fibers is common to all applications of fiber optic technology in the communications and sensor fields. In the production of low-loss optical couplers, special attention must be paid to the manufacturing process to insure that couplers can be made with acceptably insertion losses. Many methods of fabricating low-loss couplers have been proposed wherein a biconical taper fiber is utilized in the design of optical waveguides.
There is an ongoing effort to provide couplers that have low insertion losses and a method of manufacturing these waveguides that improves the overall uniformity of the couplers yielded. It is also desirable to provide a method of manufacturing optical waveguides where the coupling ratio may be varied to predetermined specifications.
Generally in the manufacture of optical waveguides, such as couplers, the optical fibers are secured in apparatus in a predetermined position, a heat source is then applied to fuse the fibers together, and a pulling or tensioning means is applied to place the fibers under a predetermined tensile load to draw the fibers to obtain the operating characteristics desired. This manufacturing process is difficult to control in a precise manner because of problems in alignment, controlling temperature and diameter reduction, and minimizing the high losses in coupling or transferring the optical signal from one fiber to another. It would be desirable if there were provided a method and apparatus that could manufacture fiber optic couplers that minimize some of these errors and produce a coupler having low insertion losses and highly predictable coupling ratios.